Monday, 21 December 2015

Scuba Diving Equipment

Scuba
diving is a mode of underwater diving in which a scuba diver uses a self-contained
underwater breathing apparatus (scuba) to breathe underwater. Unlike other
modes of diving, which rely either on breath-hold or on breathing gas pumped
from the surface, scuba divers carry their own source of breathing gas, usually
compressed air, allowing them greater freedom of movement than with an airline
or diver's umbilical and longer underwater endurance than breath-hold.Scuba Diving Equipment:

Rebreathers

The
closed-circuit rebreathes were first developed for military use, due to their
stealth advantages. The first commercially successful closed-circuit scuba was
designed and built by English diving engineer, Henry Fleuss in 1878, while
working for Siebe Gorman in London. His SCBA (self-contained breathing
apparatus) consisted of a rubber mask connected to a breathing bag, with
(estimated) 50-60% O2 supplied from a copper tank and CO2
scrubbed by rope yarn soaked in a solution of caustic potash; the system giving
a duration of about three hours.

Sir
Robert Davis, head of Siebe
Gorman, perfected the oxygen rebreathe in
1910 with his invention of the Davis Submerged Escape Apparatus, the first
practical rebreather to be made in quantity.

Rebreathers
have been increasingly used by civilians for recreation, especially since the
end of the Cold War. This reduced the perceived risk of attack by Communist
Bloc forces, including by their
combat divers. After that, the world's armed forces had less reason to
requisition civilian rebreather patents, and automatic and semi-automatic
recreational diving rebreathes started to appear.

Open-circuit scuba

The first
commercially successful scuba sets were the Aqualung twin hose open-circuit
units developed by Emile Gagnan and Jacques-Yves Cousteau in 1943, in which
compressed air carried in back mounted cylinders is inhaled through a demand
regulator and then exhaled into the water adjacent to the tank.

The single
hose two stage scuba regulators trace their origins to Australia, where Ted
Eldred developed the first example of this type of regulator, known as Porpoise
scuba gear. This was developed because patents protected the Aqualung's twin
hose design. The single hose regulator separates the demand valve from the
cylinder, giving the diver air at the ambient pressure at the mouth, rather
than ambient pressure at the top of the cylinder.